countCode.js

const data = ["FWmcfgAWxe","KnFJXGcACq","cCYApSPiX0","iHwbq2giBx","X5Ebl6sjLf","Rxc2oFCgI4","jFtFONF7NK","b8iIhVOJl6","aGlxlytbic","30e8YSgLzd","0oj65bHiHZ","NtykZPC0DH","qgj6THRgT0","rFM7G7SJbB","lcu5UKrj7w","xurxryxn5u","7XDXFJ8Axh","RuQU6EeJyi","go3SD5CYYT","c8sOoXTa59","Vh0QfTkdKk","rrYBTg4sWc","CmeWiA73ig","iM8MD2IXle","SQk4WlTLiE","wn3JhYo93i","Hlh1Amt1jo","Rd6hiOekcE","LMKIBsBBmQ","nb72pL5LKQ","8GufbXPMRb","OO5OnLzsdP","hLddf4izXl","6x8suntNs6","8VATvVOQZR","jxL8zSOcZN","87YqnuB6Mc","sqr1WbVsWv","fLC17MbW59","tJ6Z5r6mDd","iiEffxACk7","C6w4k9AS2N","9rQTNM8xmG","x4JQLDr6hd","3bYXSm7Zgo","phTYCmMxOW","isl31Fd0SN","CZItvlfdqW"];

function countCode(letter){

    const qwe = [];

    for(let i = 0; i < data.length; i++){
        if (data[i].startsWith(letter)) {
            qwe.push(data[i])
        }
    }

    return qwe.length
}

console.log(countCode("i"));